1. Field of the Invention
The present invention relates to a technology for assigning an address to a communication node.
2. Description of the Related Art
Recently, an ad-hoc network has been utilized that can establish data communications between a plurality of communication nodes without infrastructure.
However, in the ad-hoc network environment, a network is configured without infrastructure. Thus, a protocol for automatic Internet Protocol (IP) address assignment such as a dynamic host configuration protocol (DHCP) on a wired network cannot be used.
Therefore, a communication node connected to the ad-hoc network needs to set as its own IP address an address that is not used by other communication nodes connected to the ad-hoc network.
Japanese Patent Application Laid-open Nos. 2004-274750 and 2005-12761 disclose conventional technologies in which a communication node periodically transmits information on its IP address to other communication nodes that constitute an ad-hoc network. Upon receipt of the information, each of the communication nodes determines whether the IP address is coincident with its own IP address. When the IP addresses are coincident, the communication node sets a new IP address, and transmits the new IP address to other communication nodes. Accordingly, duplicate use of the same IP addresses by communication nodes is prevented.
In the conventional technologies, however, an IP address cannot be efficiently assigned to a communication node connected to the ad-hoc network. It takes some time before data communications is initiated between communication nodes.
Specifically, in the process of detecting duplicate use of the same IP address and reassigning a new IP address, it may occur that the new IP address is also used by another communication node. When a plurality of communication nodes are connected to the ad-hoc network, it is highly likely that the communication nodes are assigned the same IP address. This results in the repetition of a series of operations: assignment, detection, and reassignment, until an IP address used by none of the communication nodes is assigned.